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1.
In the current paper, we produce a new metal–organic framework (MOF) based on Zr metal, [Zr-UiO-66-PDC-SO3H]FeCl4, via an anion exchange method, which is fully characterized by FT-IR, SEM with elemental mapping and EDX, FE-SEM and TEM. Furthermore, the use of [Zr-UiO-66-PDC-SO3H]FeCl4 as a porous catalyst was examined for the one-pot synthesis of novel dihydrobenzo[g]pyrimido[4,5-b]quinoline derivatives by reaction of 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione, 2-hydroxynaphthalene-1,4-dione and various aldehydes at 100 °C with good to excellent yields.We produce a new metal–organic framework, [Zr-UiO-66-PDC-SO3H]FeCl4, via an anion exchange method, and test its use as a porous catalyst. 相似文献
2.
An efficient method to synthesize benzothieno[3,2-b]benzofurans via intramolecular dehydrogenative C–H/O–H coupling has been developed. Good to excellent yields (64–91%) could be obtained no matter if the substituted group is electron-donating or electron-withdrawing. Notably, three-to-six fused ring thienofuran compounds could be constructed using this method. A reaction mechanism study showed that 1,1-diphenylethylene can completely inhibit the reaction. Therefore, it is a radical pathway initiated by single electron transfer between the hydroxyl of the substrate and the copper catalyst.The construction of benzothieno[3,2-b]benzofurans via novel dehydrogenative C–H/O–H coupling reaction has been developed with excellent yields. Furthermore, three-to-six fused ring thienofuran compounds could be constructed. 相似文献
3.
In this paper, a simple and practical synthesis of benzo[e]benzo[4,5]imidazo[1,2-c][1,3]thiazin-6-imine tetracyclic heterocycles via a CuI nanoparticle-catalyzed intramolecular C(sp2)–S coupling reaction is presented. This strategy provides a straightforward method for synthesizing analogs of the anti-HIV drug 3,4-dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine (PD 404182). The reaction rate and yield were increased by employing CuI nanoparticles.We proposed a practical synthesis of analogs of the anti-HIV drug 3,4-dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine via a CuI nanoparticle-catalyzed intramolecular C(sp2)–S coupling reaction. 相似文献
4.
Quan-Bing Wang Shi Tang Ying-Jie Wang Yue Yuan Tieqiao Chen Ai-Qun Jia 《RSC advances》2021,11(28):17206
A PIDA mediated intramolecular oxidative C–N coupling and subsequent detosylative aromatization to afford indolo[2,3-b]quinoline derivatives has been developed. This tandem reaction provided an efficient method for the synthesis of valuable indolo[2,3-b]quinoline derivatives.Under mild conditions, PIDA mediated oxidant C–N coupling to afford indolo[2,3-b]quinoline derivatives has been developed with a decent substrate scope.Indolo[2,3-b]quinolones are a kind of important poly-fused heterocycle, commonly occurring in many natural products and synthetic drugs (Fig. 1).1 These compounds usually display diverse biological activities2 such as anticancer,3 antiplasmodial,4 molluscicidal,5 and antimalarial activity6etc. Due to their importance, their efficient synthesis attracts chemists'' interest and many synthetic methods have been developed.7 Among these established methods, indolo[2,3-b]quinolones are usually prepared through construction of a pyridine cycle with indole derivatives as the starting materials catalysed by transition metals.8 The more attractive metal-free methods avoiding the metal contamination of products have also been reported.9 Initially, indole-3-aldehydes or o-amino benzaldehydes were used; these compounds were usually unstable and difficult to prepare. In 2012, Liang and co-authors reported an efficient synthesis from indoles and o-sulfamidoaryl ketones.10 This reaction is a two-step process involving iodine-promoted amination/intramolecular cyclization and subsequent detosylation in 12 M HCl. The direct intramolecular cyclization of indole derivatives through oxidative C–N coupling and detosylative aromatization was also reported. In 2016, Sekar and co-authors pioneering used Ts (4-benzenesulfonyl) as the activating group for amino group under heat (Scheme 1A).11 In this reaction, 1.2 equiv. sublimed and corrosive I2 was used as the oxidant and 2 equiv. Cs2CO3 as the base, only 5 examples were demonstrated. Very recently, using the special Ns (4-nitrobenzenesulfonyl) to activate the amino group, Ishihara and co-authors achieved the reaction at room temperature through iodine catalysis (Scheme 1B).12 This reaction required 3–5 equiv. hazardous TBHP as the oxidant and relatively long reaction time (12–48 h).Open in a separate windowFig. 1Selected examples of bioactive indolo[2,3-b]quinoline derivatives.Open in a separate windowScheme 1Metal-free intramolecular cyclization for preparing indolo[2,3-b]quinolones.PhI(OAc)2 is a common oxidant used in annulation reactions due to its easy operation and environmental benignity.13 With our continuing interest in exploding synthesis of heterocyclic compounds,14 we envisioned that this reaction might also be achieved with the use of PhI(OAc)2 as the oxidant. Indeed, it worked well under the mild reaction conditions with the amino group being activated by 4-chlorobenzenesulfonyl group (Scheme 1C).Stirring a mixture of 1a and 1.2 equiv. PhI(OAc)2 in DCM at room temperature for 12 h under an Ar atmosphere gave the product 2a in 10% yield († for details).Optimization of the reaction conditionsa
Open in a separate windowaReaction condition: 1a (0.2 mmol), PhI(OAc)2 (0.24 mmol), solvent (2 mL), rt, Ar, 12 h.bIsolated yield.cPhI(TFA)2 was used instead.d0.4 mmol PhI(OAc)2.e1b was used instead.With the optimal reaction conditions in hand, we then investigated the substrate scope (
Entry | Temp. (°C) | Solvent | Yieldb (%) |
---|---|---|---|
1 | rt | DCM | 10 |
2c | rt | DCM | Trace |
3 | rt | THF | 28 |
4 | rt | Dioxane | 19 |
5 | rt | PhCF3 | 16 |
6 | rt | TFE | 51 |
7 | rt | HFIP | 67 |
8d | rt | HFIP | 15 |
9 | 0 | HFIP | 43 |
10 | 0–rt | HFIP | 82 |
11e | 0–rt | HFIP | 86 |